I think HER point was that, if you are a woman and want to have a family (and don't already have one when you start this process), it will be tougher to start a family as an older cards fellow if you are the one giving birth to the child than the one fathering it.
If you already have a family that will be well on their way to college, this will not be nearly as big of an issue.
As an example, of the dozen-ish cards fellows at my institution, 3 are women. All are single and have no kids. Of the men, all but 3 have kids (one is separated geographically from his wife because of training, one is single, the other is gay). Of the 10 hem/onc fellows OTOH, 4 are women, 1 of whom is single-ish, two are pregnant, one has 2 kids and all but one of the men have kids.
If you go straight through in cards, it will be as hard as in gen surg to have a family. Women will take the brunt of this. If you are a non-trad, this will likely be less relevant to you.